The present invention relates to surgical instruments and in particular to surgical instruments for guiding saws and other cutting tools used in bone surface preparation.
Existing cutting tools have a saw blade with a cutting edge which is typically serrated at its distal end. The saw blade is secured to the cutting tool at its proximal end for oscillation in a side-to-side motion and driven by a driving mechanism such as a shaft coupled to a motor. To cut or resect a bone, the saw is oscillated at high speed around an axis of oscillation which causes the blade to cut through the bone.
To facilitate accurate cutting of the bone, many surgical instruments are fixed in a known position relative to a patient. One way of doing this uses a cutting block. Cutting blocks are typically affixed to a patient's bone in a position such that they can guide cutting and resection of the bone surface for receiving an implant.
Existing cutting blocks may include a guide, recess or cutting groove for the saw blade in order to correctly position and guide the cutting tool during the surgical procedure.
Although this takes some skill and practice a surgeon is able to produce a cut that is reasonably accepted as predictable.
Such cutting blocks can exhibit a number of limitations or disadvantages:                Friction against the surface of the cutting block can lead to wear particles being produced;        Friction can generate heat that leads to thermal necrosis of the bone and also to risk of injury or burns to the surgeon;        A lack of visibility of the saw as it approaches the bone;        Saw blade excursion and thickness may be limited by the dimensions of the recess;        Some surgeons prefer to use narrow blades, while some use wider blades known as “whale tails”, but not all of these blades are compatible with all recesses;        Recesses can become wider as they are used which reduces the accuracy over time;        In saw slots which are not a constant depth, the engagement length between blade and block changes as the blade moves along the cut, reducing and increasing the amount of play;        Cutting blocks can become damaged over time;        Surgeon preferences vary which requires manufacturers to develop and manufacture a number of designs and variants;        Each recess is made very accurately which increases costs; and        Cutting blocks require replacement significantly often.        